Public Version
High-Speed USB Host Subsystem
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Bits
Field Name
Description
Type
Reset
11
OCPM
Overcurrent protection mode.
RW
1
Note: The bit must not be used, and is always written to
with its default (reset) value as the hardware overcurrent
inputs are tied off at device level.
10
DT
Device type.
R
0
Always reads 0x0: Indicates that the USB host controller
implemented is not a compound device.
9
NPS
No power switching
RW
0
0x0: VBUS power switching is supported, either per-port
or all-port switched per the power
0x1: VBUS power switching is not supported, power is
available to all downstream ports.
8
PSM
Power switching mode.
RW
1
0x0: Indicates that all ports are powered at the same time
0x1: Individual port power switching is supported
7:0
NDP
Number of downstream ports.
R
0x03
These bits specify the number of downstream ports
supported by the root hub. It is implementation-specific.
The minimum number of ports is 1. The maximum
number of ports supported by OHCI is 15.
Table 22-201. Register Call Summary for Register HCRHDESCRIPTORA
High-Speed USB Host Subsystem
•
High-Speed USB Host Controller Functionality
•
High-Speed USB Host Subsystem Register Summary
Table 22-202. HCRHDESCRIPTORB
Address Offset
0x0000 004C
Physical Address
0x4806 444C
Instance
OHCI
Description
HC Root Hub B Register
Type
RW
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
PPCM
DR
Bits
Field Name
Description
Type
Reset
31:16
PPCM
Port power control mask. Each bit defines whether a
RW
0x0000
corresponding downstream port has port power controlled
by the global power control. When set the port's power
state is only affected by per-port power control. When
cleared the port is controlled by the global power switch.
If the device is configured to global switch mode this field
is not valid. bit 0: Reserved, bit 1: Ganged-power mask
on port 1, ..., bit 15: Ganged-power mask on port 15
15:0
DR
Device removable. Each bit defines whether a
RW
0x0000
corresponding downstream port has a removable device.
When cleared the attached device is removable. When
set the attached device is not removable. Bit 0:
Reserved, bit 1 : Device attached to port 1, &, bit 15:
Device attached to port 15
Table 22-203. Register Call Summary for Register HCRHDESCRIPTORB
High-Speed USB Host Subsystem
•
High-Speed USB Host Controller Functionality
•
High-Speed USB Host Subsystem Register Summary
•
High-Speed USB Host Subsystem Register Description
:
3338High-Speed USB Host Subsystem and High-Speed USB OTG Controller
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated